Pages looking distorted on older browsers

Hi,

On my site, I applied an Artisteer-generated theme that looked fine on my browser – Google Chrome v 39.x and IE 11.x (with auto-updates). However, I’m getting reports from an associate who checks the site with older Browsers (IE, Chrome, Firefox) and the pages are looking distorted and scrunched.

My initial steps were to upgrade WP to the latest version and re-apply the Artisteer-generated theme. In addition, I also updated all of the plugins so everything is now current.

One possible cause for the distortions may be something in the theme got corrupted and re-applying the theme would fix it.

Is there anything else I should check or consider?

The site is https://glutenfree-lowglycemic-diet.com.

Suggestions would be greatly appreciated.

I chose this forum because it has to do with themes. If this is in the wrong place, let me know.

Thanks,

Broadlighter